The subject matter disclosed herein relates to an electrical generator connection and in particular to an electrical generator connection for underground utility distribution networks and distribution substations.
Electrical utilities have a number of metrics that are used to track performance and customer satisfaction. These metrics, which include the system average interruption frequency index (“SAIFI”), the customer average interruption duration index (“CAIDI”), and for some utilities, the momentary average interruption frequency index (“MAIFI”). SAIFI measures the average number of interruptions that a customer would experience during a time period, such as a year. CAIDI measures the duration of the interruption that a customer would experience, and is generally a few hours per year. MAIFI measures the number of power interruptions that have a duration of less than five minutes that a customer would experience during a given time period.
In some instances, electrical utilities may be financially penalized in the event that certain metrics or conditions are not satisfied. For example, an electrical utility may be fined if a certain percentage of the customers connected to the electrical utility network customers are without electrical power. To maintain electrical network performance metrics at desired levels, the electrical utility may utilize auxiliary generators to supply electrical power to customers that downstream from an event that has interrupted the electrical power delivery service. They even may include a service interruptions due to equipment damage (e.g. a utility pole knocked down, or contractor damage to an underground line) and/or excessive electrical demand on the network (e.g. days with high temperatures and large air conditioning loads).Since an auxiliary generator cannot be allowed to flow electrical power into the general electrical grid, the portion of the network powered by the auxiliary generator needs to be electrically isolated. In some instances, customers are connected to a section of the grid that is easily isolated, such as customers connected to a 4 kV grid for example since this type of network may be easily isolated and an auxiliary generator connected. However, most customers are connected to a secondary distribution network to which connecting auxiliary generators is difficult. The only means is to isolate the customer's cable from the grid by entering the manhole and connecting the generator leads to a single customer supplied by the service cable. Other nearby customers that may be out of lights will each require their own individual generator connection to their supply or service cable.
To connect an auxiliary generator to a secondary distribution network, utility personnel enter a distribution manhole and cut the secondary cable or low voltage cables. A standard generator connector is then manually coupled to the cut end of the secondary cable. The auxiliary generator is connected to the isolated distribution customers and operations initiated to supply electrical power to the distribution customer(s). It should be appreciated that this operation may have to occur during less than desirable conditions (e.g. a heat wave) when the electrical cables being cut are heavily loaded. To return the secondary distribution network, the operation of the auxiliary generator is halted and disconnected from the secondary cable. The secondary cables must then be re-spliced back together to restore electrical service. Sometimes, this causes the crews to re-splice all the secondary (or 120V) cables in the manhole.
While existing methods of connecting auxiliary electrical generators to electrical utility distribution networks are suitable for their intended purposes the need for improvement remains, particularly in providing a system for quickly and easily isolating a portion of an electrical network and connecting an auxiliary electrical generator.